1. Field of the Invention
The present invention is directed to a programmable radio which includes a receive module and a transmit module that can be digitally reconfigured to operate over a broad radio band and with different signal formats. More particularly, the present invention is directed to a transmit module of a programmable radio, the transmit module being reprogrammable to transmit different types of radio functions.
2. Description of the Related Art
Many commercial and military situations require radio function for multiple communication, navigation and identification (CNI) functions to be performed at a single location. Such radio function can include radio function for a conventional instrument landing system (ILS), a conventional air traffic control radar beacon system (ATCRBS), a conventional Mode S interrogation system or a conventional VHF AM system. Therefore, there are many air vehicles, ships, space platforms, ground-mobile vehicles, ground-mobile personnel, fixed stations and communication hubs that require multiple radio functions at a single location. An integrated radio system that may perform communication, navigation and identification (CNI) radio functions is used to perform these multiple radio function.
At one extreme, a communication, navigation and identification (CNI) radio system comprises an independent and different-type radio channel for each type of radio function. At the other extreme, an integrated programmable radio system cross-couples various elements of multiple channels, thereby resulting in a highly complex system of tightly coupled resources. Both approaches, and hybrids of the two approaches, have advantages as well as major disadvantages. For example, an independent channel system must have a separate, complete backup system for each critical system. Thus, a complete backup system is typically provided for a critical instrument landing system (ILS). This is very costly. Moreover, cross-coupled systems are extremely difficult to maintain due to difficulties of fault isolation.
Thus, there is a need for improved partitioning of radio system elements that allows the use and reuse of identical common programmable components or modules in a cost effective manner and without costly fault identification. More particularly, there is a need for a radio system having a common transmit module which can be reconfigured to perform different types of radio transmission.